We chose to further characterise thymidylate synthase (TYMS), as it is non-essential and can be inhibited pharmacologically with Pemetrexed (TYMS inhibitor), which is currently used as a cancer therapeutic for pleural mesothelioma and non-small cell lung cancer and is thought to act to slow DNA replication by nucleotide depletion or through accumulation/misincorporation of dUMP in DNA48,49. The gene discussed is TYMS; the disease is pleural mesothelioma.